Abstract

South Pacific thermocline waters are transported in the westward flowing
South Equatorial Current from the subtropical gyre center toward
the southwestern Pacific Ocean—a major circulation pathway that redistributes
water from the subtropics to the equator and to the southern ocean.
The transit in the Coral Sea is potentially of great importance to tropical climate
prediction because changes in either the temperature or the amount of water
arriving at the equator have the capability to modulate the El Niño-Southern
Oscillation (ENSO; glossary of acronyms at the end of the document) cycle and
thereby produce basin-scale climate feedbacks. The southern fate of thermocline
waters is, comparably, of major influence on Australia and New Zealand’s
climate; its seasonal and interannual evolution influences air-sea heat flux and
atmospheric conditions, and it participates in the combined south Indian and
Pacific Ocean "supergyre." Substantial changes of this circulation have been
observed over the past 50 years, and are continuing in global climate projections.
The subtropical gyre has been spinning up in recent years with possible
consequences for ENSO modulation and for the East Australian Current (EAC),
whose influence has moved south, dramatically affecting the climate and biodiversity
of Tasmania.